The transmission of a signal and the transmission of electrical power, i.e. power supply, is used, for example, in high voltage applications, such as in a gantry of computed tomography systems. High voltage switches are used, for example, to provide the necessary electrical energy to an X-ray tube as well as the respective switching commands for the operation of the X-ray tube. U.S. Pat. No. 4,685,118 describes a circuit for controlling energization of a cathode. A switching transistor is coupled to a photodiode outside the housing via a light pipe. It has been shown, for example, that a continuous cycling between on and off of a switch can mean a restriction with respect to possible switching schemes. A further disadvantage can be seen in the fact that separate signal transmission devices result in complex design structures as well as in increased manufacturing costs.